Semiconductor substrate processing is typically performed by subjecting a substrate to a plurality of sequential processes to create devices, conductors and insulators on the substrate. FIG. 1 illustrates a prior art semiconductor processing system 100 for performing sequential processes. These processes are generally performed in a processing chamber configured to perform a single step of the production process. In order to efficiently complete the entire sequence of processing steps, a number of processing chambers 108 are typically coupled to a central transfer chamber 104 that houses one or more robots 112 to facilitate transfer of the substrate 124 between the processing chambers 108. A semiconductor processing platform having this configuration is generally known as a cluster tool, examples of which are the family of CENTURA® and ENDURA® processing platforms available from Applied Materials, Inc. of Santa Clara, Calif.
Generally, a cluster tool 100 consists of a central transfer chamber 104 having one or more robots 112 disposed therein. The transfer chamber 104 is typically surrounded by one or more processing chambers 108, at least one load lock chamber 106. The processing chambers 108 are generally utilized to process the substrate 124, for example, performing various processing steps such as etching, physical vapor deposition, chemical vapor deposition, and the like. Processed and unprocessed substrates 124 are housed in a substrate storage cassette 130 disposed in a factory interface 102 coupled to the load lock chamber 106.
The load lock chamber 106 is isolated from the factory interface 102 and the transfer chamber 104 by slit valves 116. Substrates 124 enter the transfer chamber 104 from the substrate storage cassettes 130 one at a time through the load lock 106. The substrate 124 is first positioned in the load lock 106 after the substrate 124 is removed from the cassette 130. The load lock 106 is then sealed and pumped down to match the operating pressure of the substrate transfer chamber 104. The slit valve 116 between the load lock 106 and transfer chamber 104 is then opened, allowing the substrate transfer robots 112 to access the substrates 124 disposed in the factory interface 102. In this fashion, substrates 124 may be transferred into and out of the transfer chamber 104 without having to repeatedly re-establish transfer chamber vacuum levels after each substrate 124 passes through the load lock 106 or processing chambers 108. Although cluster tool 100 includes six processing chambers 108, any number may be used.